The invention relates to a boom for use in spreading a fluid material by mounting the boom on an agricultural tractor vehicle for transportation across the ground, the boom including a tip portion which can be retracted or folded rearwardly relative to the collinear extent of the boom.
The present invention is presently concerned with a boom for a sprayer that could also be used in other distribution systems for example for distributing particulate or granular materials in an air stream.
Many different designs of booms have previously been proposed for devices of this type. Many booms include a tip portion which can retract or move rearwardly if impacted by an obstacle in order to reduce the possibility of damage of the boom should the operator make a mistake and the impact of the boom, particularly adjacent its tip, on an adjacent obstacle. It will of course be appreciated that the operator needs to maneuver the vehicle so that the tip portion moves as close as possible to the obstacle so that the spraying action occurs also in the area of the obstacle but this in some case leads to the possibility of error, particularly if the boom is of a longer length for example greater than 70 feet from the tip of one boom to the tip of the opposed boom on the opposite side of the tractor vehicle.
Most break-away tips of this type are pivoted about an axis which is inclined to the vertical so that gravity tends to redirect the tip portion back into its collinear working position. However springs can also be used alone or in addition to gravity to effect the return. In most cases the tip portion includes a friction latching arrangement which simply holds the tip portion in place by friction rather than a positive locking action since this can be readily released by the impact. Examples of a break-away tip portion of this type are shown in a brochure by Tyler showing the "Patriot" Applicator;
However this arrangement is generally unsatisfactory in that normal vibration can cause release so that the operator tends to overtighten the clamp to prevent inadvertent release until the clamp is so tight that it is not released by impact.
It is known from brochures by Flexicoil showing the "65 Field Sprayer" and Knight showing the KM100 Field Sprayer to provide an impact tube in advance of the break-away tip so that the impact tube absorbs the impact from the obstacle and causes release of the break-away or retraction movement. In the Flexicoil arrangement, the whole of the boom breaks away and folds rearwardly. However this is used with a relatively slow moving tow-behind arrangement and provides no energy absorption of the impact energy on the boom.
A further concern for long booms of this type is that of folding the boom for movement to a transport position retracted against the sides of the tractor.
Some folding systems simply pivot the boom about an axis adjacent the tractor so that it folds inwardly to lie along side the tractor. Examples of booms of this type are shown in the Knight brochure and in a brochure by Melroe showing the "Spray Coupe". A brochure by John Deere showing the 6500 self propelled sprayer provides a vertical folding action to form a complex "X" arrangement of the boom in the folded position.
Another example of a folding action is shown in the brochure of Hagie showing the 284 sprayer in which the boom has an inner portion and an outer portion with the outer portion pivotally mounted at an end of the inner portion for folding action in which the outer portion pivots upwardly and inwardly about a generally horizontal axis to fold to a position on top of the inner portion, following which the two folded portions are pivoted about a vertical axis to fold along side the tractor.
The present invention is particularly but not exclusively designed for use as a conversion system for mounting a sprayer kit including a tank and booms on a conventional swather tractor. A previous example of this type of arrangement has been manufactured and sold by Setter Manufacturing Division and shown in a brochure entitled "Setter's Swather Conversion High Clearance Sprayer" in which a tank and boom are provided as a separate assembly for mounting on the forwardly extending supporting arms of the conventional swather tractor.
A swather tractor of this type is manufactured by the present assignees MacDon and is shown in a brochure entitled "Premier 2900".
The present invention is particularly but not exclusively concerned with longer booms of the order of 90 feet in which the danger of impact with an obstacle is more serious and in which the folding action is more problematic in that, even if folded as inner and outer boom portions, the length of each portion can be as much as 20 feet so that the portions are themselves unwieldy and dangerous.